I have a 2000 Mazda Protege with about 93,000 miles on it. The check engine light has come on. Took it to a mechanic, he said that the OBD shows that it’s either the O2 sensor or the catalytic converter. After checking the O2 sensor, it’s not that, so it must be the catalytic converter. Repair estimate is $850. Checked the Blue Book and it says that the car is worth $1600 in fair condition. For that kind of money I took it for a second opinion. Different mechanic says the same thing; catalytic converter and some sort of connection mechanism is rotted out; repair estimate $1000.
Two different guys, both saying it’s not the O2 sensor. Both say that it’s not going to hurt the car, but that it won’t pass its next Emissions test which will probably be in February 2010, about 1 month away. 
If I try to purchase a new car, is the fact that that the CEL is lit up going to affect anything? Since the car is already 10 years old, would it even be resold, or it is destined for the scrap yard anyway?
Or, should I put in the $900, cross my fingers, and hope that this car is drivable for another 20-30K miles? If I start looking at all the upcoming maintenance that’s due on the car (one mechanic said that the timing belt should probably be replaced at 90K, so I’m overdue for that apparently), is it no longer cost effective to keep this one going?
We’ve been looking at something like the Ford Fusion hybrid or Prius.
There’s also apparently some sort of IRS tax break. Too many decisions!
Math test: how many $333 car payments will $900 cover? How many will $1500 cover?
If the rest of the vehicle is in good shape, I’d get the work done. I’d go to the first guy because he actually checked the O2 sensor rather than just the codes. I like that.
On the other hand, if you’ve been thinking about getting yourself a new Prius for Xmas this might be a good excuse…
Now might be a good time to trade you '00 Mazda in for a new car. I sense you are not going to be happy with the more frequent repairs that any 10 year old car with 100K miles will require.
The Mazda is a pretty decent car and a new timing belt is standard stuff. Once the cat is replaced the car should be fine for awhile. So, if you want to avoid 4 to 5 years of car payments make the repairs. If you don’t mind payments and value not having to deal with a repair bill once or twice a year then get a new car.
At work i’ve driven vehicles with 200, 250, 300, even 400k miles all of which were in excellent condition; thus your Mazda is just now getting broken in with its modest 93k.
If your car is in good shape and you’ve been taking care of it (doing all the maintenance, not just changing the oil), then you should have the repairs done and keep the car.
I think you will find the FFH and TP downright boring to drive compared to the mazda.
Just my $0.10 worth…
Reset the light (by disconnecting the battery) and see how long the light stays off. Maybe long enough to get it past that emissions test…
Failing that, find an independent muffler shop who should be able to install a new aftermarket CAT and eliminate the flex coupler for FAR less than $850…Usually, those expensive braided stainless flex couplers can be eliminated without any serious problems. It’s worth a try…
My wife has two friends who own just such cars. One is an economist, the other in health care. Both tell me this is the most bullet-proof little car they have ever owned.
Go to a mechanic who can actually diagnose correctly what exactly you need. If the rest of the car is well maintained, I would fix it. As pointed out, whatever it costs will only be a few new car payments.
You might want to shop around for prices on replacement of the converter. An after market converter put in by a good independent mechanic may well reduce the price.
In any case, consider how many payments you need to cover the cost of the maintenance. Then consider how many more payments will still be due.
There is a CAUSE for the catalytic converter “going bad”. The CAUSE needs to be addressed. If the cause is not remedied, the new catalytic converter will, likewise, “go bad”. Did any “mechanic” mention that?
Apparently the second mechanic said the cause is holes in the converter and the flexible coupling section in front of it. Seems reasonable. Nothing like a few holes to alter the Oxygen balance in the exhaust stream.
$900-1000 seems to me like an awful lot for a catalytic converter replacement for this car – except maybe in California. 49-state replacement units seem to go for $100-$300. I doubt the coupling section is more than $100. And there surely isn’t $500-600 worth of labor there. Maybe I’m missing something or there are more problems?
I didn’t get an answer regarding why the cat went bad; as a layman I thought that a catalytic converter was essentially just a muffler filled with platinum that helped clean the exhaust.
The first mechanic quoted $600 for the converter, the rest being labor and tax for a $850 estimate. The second said around $400 for the converter and that it needs a new downpipe, then labor and tax would bring the total to $1000.
Other than that, I don’t believe there’s anything else fundamentally wrong with the car.
OK, now that’s interesting.
The car sat in the O’Hare remote parking lot for 5 days, so it was essentially at 0 degrees and covered in snow. As I drove home, I realized that the light wasn’t on. Now, it’s possible that the light has burned out, but is there some other reason that exposure to cold for so long has altered something? The light stayed off throughout the 45 minute trip, and so the car was warmed up by the time I pulled into my garage.
Maybe you are lucky and some hose was loose and one of the mechanics intentionally or accidently got it put back on. It can happen. Good luck.
So the weirdness continues. The light has been off for about two weeks and I had my emissions test. The car passed!
So I’m a bit befuddled. Did I ever even have an issue? Did two separate mechanics try to get between $800-$1000 from a car that wasn’t really broken in the first place? I would think that if the cat / pipes were actually broken then the car would have failed emissions.
Could “bad gas” have caused this somehow?
Yes, bad gas could have been the issue. I have a friend that had a similar problem with her Toyota Corolla. Buying gas at one particular station that always had ‘cheap’ gas (usually 4 cts cheaper than the others) would turn the CEL on. Gassing up at another station closer to her house, the CEL goes off and stays off. She decided to avoid that one station from now on.